This invention relates generally to a baler for forming cylindrical bales of crop material, commonly referred to as a round baler. More particularly, this invention is directed to an improved twine arm for round baler twine wrapping apparatus.
Balers of this type have a bale forming chamber defined by an apron comprising an array of belts, chains, and/or rolls within which the cylindrical bale is formed. Crop material such as hay is picked up from the ground as the baler traverses the field and is then fed into the chamber where it is rolled up to form a compact cylindrical bale. Twine wrapping apparatus is provided for securing the bale in its compacted form while still inside the bale forming chamber prior to ejecting the bale from the chamber onto the ground for subsequent handling. Wrapping apparatus commonly utilizes one or more twine dispensing arms for feeding twine to the circumference of the formed bale. Lateral traversal of the arm or arms results in a helical wrap around the bale as the bale is turned in the chamber.
There are various prior art approaches for wrapping twine around round bales to maintain its compact integrity when ejected. In most or all of these it is important that the initial free end of the twine strand, commonly referred to as the "tail", is consistently of sufficient length to assure that the wrapping operation is immediately and properly carried out. To accomplish this the twine is sometimes clamped after it has been severed at the completion of the previous wrapping operation. Clamping mechanisms are commonly utilized in the wrapping apparatus and in some instances are mounted on the twine arm to prevent loss or shortening of the tail due to slack in the system when the twine is cut.
Also of concern in twine wrapping apparatus is convenience of initially threading twine in a new baler or rethreading the twine when the supply becomes depleted. The twine is stored in balls located on the baler in compartments from which the twine is fed out to the wrapping apparatus. It is then guided along a path to the twine tube and ultimately to its dispensing end. During twine threading, as the lead end is drawn along its path from the storage compartment to and then through the wrapping apparatus, if clamps are employed they must be disengaged to permit threading and then reengaged to permit normal operation. When twine is pulled during wrapping from the dispensing tube which is fed, via the twine path, from the supply, it should not be unduly impeded by the clamp or clamps disposed along its path.
If tensioning of the twine is desired, which in many instances is variably applied, it could be an independent function of the clamps. Usually some kind of tensioning device is provided to apply tension to the twine as it is being wrapped around the bale to improve bale compactness and stability. If such tensioning causes hesitation in the grasping of the tail, wrapping start is delayed and baler reliability is affected. Thus, controllably tensioning and tail length are important interrelated aspects of reliable round bale wrapping.